in June 2005 Wikipedia had a total of 68,682 total contributors. Wikipedia founder Jimmy Wales is reported to have told a library group that month:

50% of all Wikipedia edits are done by 0.7% of users

1.8% of users have written more than 72% of all articles

If we also add evidence from Bradley Horowitz that roughly 1% of Yahoo's user population starts a Yahoo Group, we seem to have The 1% Rule: Roughly 1% of your site visitors will create content within a democratized community. (Horowitz also says that some 10% of the total audience "synthesizes" the content, or interacts with it.)

The overriding lesson: Avoid marginalizing the 1 Percenters as statistically insignificant, unrepresentative of the total audience or simply the lunatic fringe. If anything, the 1 Percenters may represent the leading indicators of how well your brand is being adopted, synthesized and vocalized.

This post Are you a 1 Percenter? does a fabulous job of summarizing all the responses and input from other posts around the web. No need to re-create that here, just go there.

The part that says 10% of your site visitors synthesize the content is something I've been driving at for a while. Our software needs to accomodate three types of visitors:

The writer

The synthesizer (editor, masher, cross-linker)

The reader

Each type of visitor has a very different kind of perspective, attitude, expectation and need.